In the known Claus process, gases which contain H.sub.2 S are desulfurized and elemental sulfur is produced. Details have been described, e.g., in Ullmanns Encyclopedia of Technical Chemistry, 4th Edition (1982), volume 21, on pages 8 to 26, and in Published German Application 37 35 002.
It has previously been believed that, for an after-treatment of the exhaust gases from the Claus process plant and to ensure that the gases, which in addition to H.sub.2 S and SO.sub.2 contain COS and CS.sub.2, will be desulfurized to a high degree, it is necessary to provide a separate catalytic stage for effecting a hydrogenation and hydrolysis at the same time, as is described in Published German Application 37 35 002 and, e.g., also in European Patent 0 054 772.